1. Field of the Invention
The invention relates to the field of tools for crimping a terminal to an end of an electrical conductor, and more particularly, to a crimping tool having a handle pivotable about a displaceable fulcrum so as to reduce the force required to operate the tool through a complete crimping cycle.
2. Prior Art
Terminals are generally attached to ends of electrical conductors by soldering or crimping. Terminals suitable for crimping have a channel or barrel adapted to receive an end of a wire or cable conductor therein. During crimping, the end of the conductor having the terminal thereon is disposed between a pair of opposed members which are relatively movable to tightly squeeze the workpiece between the members. The channel or barrel portion of the terminal is deformed by the tight squeezing so as to securely grip the conductor and resist separation therefrom.
Hand tools for crimping a terminal to an end of an electrical conductor are well known. Such tools generally include a pair of relatively movable jaw members which cooperate to crimp the terminal to the conductor upon actuation of a handle mechanism. In order to as sure that each crimped terminal will maintain dependable electrical contact with its associated conductor and be secure against separation therefrom, it is desirable to deform the terminal during crimping so as to achieve a certain maximum crimp height, such height depending upon the size and type of terminal and conductor being crimped. Rather than measure directly the crimp height of terminals after crimping, it is known to provide a crimping tool with a mechanism that assures that the crimping jaw members will converge to within at least a predetermined distance from each other, thus assuring that the resulting crimp height will be no greater than the desired maximum. The mechanism is engaged upon initiation of a crimping operation and prevents retraction of the jaw members away from each other until the predetermined minimum separation of the jaw members is achieved.
A problem with tools having the mechanism which prevents premature retraction of the jaws is that the hand force which must be applied in actuating the handle mechanism increases steeply during a crimping operation as the workpiece is squeezed and deformed between the jaws. The required hand force may become so high that completion of the crimping operation becomes extremely difficult or impossible for some operators. At the very least, the required hand force is usually great enough to cause muscle strain and hand fatigue for the operator performing numerous crimping operations. Muscle strain and hand fatigue can be a problem even for the operator of a hand crimping tool that does not have the retraction prevention mechanism, and long term injurious effects from repetitive crimping operations may be even more severe, e.g., tendinitis and carpal tunnel syndrome. It is desirable to provide a hand crimping tool which consistently produces a secure crimp while reducing the force which must be applied to the handle mechanism during a crimping operation.